Rolled-twisted piston ring



` I 1,546,525. R. B. WASSON ROLLED TWISTED PIsToN RING Filed May 16, 1925 2 Sheets-Sheet l @1T/toon July 21, 1925. l

, 1,546,525 R, B. WA'SSON RoLLED TWISTED PIsToN RNG 2 Sheets-Sheel'I 2 Filed May 16, 1925 9 2 7 .j ,21a Wvg/ won @Wa/am CTI Patented July 21, 1925.

UNITED STATES ROBERT B. WASSON, 0F CRANFORD, NEW JERSEY.

ROLLED -TWISTED PISTON RING.

Application filed May 16,

.To all *whomy it may concern.'

Be it known that I, ROBERT B. VASSON, a citizen of theUnited States, residing at 30G Elizabeth Avenue, Cranford, 4Jew Jersey, have invented certain new and usefuldlmprovements in Rolled-Twisted Piston Rings, of which the following is a specification.

My invention relates to metal packin'gor piston rings and more particularly vto a rolled piston ring having permanent Stresses in the ring blank imparted to the blank according to a predetermined law, around the circumference o f` the ring, the ring being condensed more to onel side of the central diametrical zone of the circumference of the ring thereby causing the ring to twist in'accordance with a definite law. @ne of the objects of the invention is to so distribute the stresses in the ring blank b v rolling that not only will the ring when confined to circular form exert a uniform A radial outward pressure but the twist will multiply the pressure without altering its uniformity and will localize the pressure at the edge ofthe ring. Attempts have been made to achieve .this result by hammering but it is not easily possible to control the hammering of the ring oit1 cent-er: an irregular twist often resulting therefrom.

These difficulties and defects are avoided -in my rolled ring. Although l shall particularly describe the invention as applied to an expanding ring. it will be understood that it may be applied to acontracting packing ring by rolling the ring on its outer circumference instead of on its inner.

lThe stresses are localized toward the inner face of the expansible ring, and at one side of the central diametrical zone thereof, the result being thatwith the ring in its lfree state, these stresses expand and twist it, setting up temporary opposing stresses in the outer ortion f until the ring has expanded into non-circular form and has twisted so that the resisting stresses are equal to the expanding stresses and the blank is in equilibrium. When the ring blank so rolled is confined Within a circular cylinder, it will translate thestresses into substantially uniform pressure per unit of Contact area, thus. securing uniform sealing pressure between ring' yand cylinder. In rolling the ring a small area of contact betweenthe'roller and .the ring 1923. Serial No. 639,314.

is preserved which is of considerable lesser extent than the area. of contact between the outer face of the ring and the holder. This enables the roller to condense the inner face of the' ring locally without objectionable distortion of the metal.

It is found by experience in peening or hammering rings, that once established, any variation in the area of the hammer point as b v dulling due to Wear will result in a variable product with an irregular expand ing force forthe ring. My invention overcomes these diticulties.`

Again the compacting effect at the points of the ring is very small but increases variably to a point opposite the split. Nevertheless, the force applied at the points must cause the metal to flow and permanently compact the inner region near the inner face. This fiow must not expand the metal laterally and any substantial change in the inner face of the blank must be prevented for this would require a correcting operation and introduce other variables, The hammer is not able to repeat its results nor to overcome the above objections. My rolling method with its delinitely applied radial force at every point of the ring and the restriction of the fiow of the met-al laterally overcomes these diiticulties. dimension ofthe ring is quite small and since only aportion of this section should. l be compacted, small commercial variatlons in the `radial dimension will cause large variations in the regularity of the force applied and will vary the resultant law of expansion of the ring. My invention overcomes this difficulty, applies the force regularly and produces a uniform piston ring.

All metals require ,time in which to How.

If the time element is too short to permitthe full amount of flow in the metal, the

As the radial result will vary as the metal is harder or softer. In some casesit is necessary to subject the inner surface of, the ring to the condensing pressure tw'o or more times. This I accomplish by treating the ring to a succession of rolling steps.

With the above and other objects in view, my invention cdnsists in the parts, improve# ments and combinations more fully pointed out hereinafter.

Turning now to the. drawings:

Fig. 1 is a section showing a rolled twisted i the condensing roller 3 may be cylindrical ring in place in its groove in the piston, the twist being greatly exaggerated; the upper portion of the ligure extends towards the explosion chamber.

Fig. 2 is a detail transverse section thru a rolled twisted ring, illustrating the condensing action of a tapered roller.

Fig. 8 is a detail transverse section, illustrating the condensing action of a cylindrical roller.

Fig. 4 is a detail transverse section thru a portion of a rolled twistedring, the ring being provided with a notch on its lower fiat face.

Fig. 5 is a side elevat-ion of a rolled twisted ring in its free state, showing Ahow the twist raises the ring from a plane surface.

Fig. 6 is a plan view of the ring.

Fig. 7 is a diagrammatic view illustrating the outline of a cross-section of the ring.

Fig. y8 is a plan view illustrating a step in the process of rolling the ring.

Fig. 9 is a section on line X Y ot Fig. 8, but with the ring and tapered roller separated, the parts being in the position just before the rolling action begins.

Fig. 10 is a section on the line X Y of Fig. 8, showing the parts while the ring is being rolled.

The process of rolling the ring so as to give it a twist will first he described,l after which a description of the ring embodying the invention will follow.

The ring 1 is condensed by rolling` one of its sides or faces by means of a condensing roller 2. As illustrated the rolling action takes place against the inner face of the ring. The condensing roller maybe tapered as shown in the drawings so that a greater pressure is applied on one half of the ring than on the other, that is to say the pressure is increased toward the bearing halt' of the ring. i. e.. the portion which bears against the cylinder wall under the twist that has been impart-ed to the ring, by the rolling action. As shown in Fig. 3,

in form, in which case the roller is positioned slightly to one side of the central diametrical plane passing thru the middle of the ring, parallel to the fiat faces of the ring and perpendicular to the axis of the ring. In

' all these cases the condensations of the metal receives the ring and the/latter 8, driving a train of mechanism which applies the rolling pressure 1n accordance with a predetermined law. As far as the ring and .processv are concerned it will be understood that the mechanism for producing the rolling pressure may be wldely varied. Themechmsm illustrated is the same as that illustrated in my copending case Serial No. 611,278, tiled The holder 9 is secured toworm wheel T thru the intermediate carrier 10 which is shouldered to receive the holder, the carrier and holder being locked together by a dowel pin.' Bolts 11 secure the carrier 10 to worm wheel 'i'.

A housing 12 is provided. having a pair of lugs 13 each having an adjusting .screw 14 which contact with stud 15 carried by block 16. The condensing roller '.2 is located in a cut-out notch in the housing. It has axial extensions which keep the roller substantially upright by contact with the top and bottom portions of the housing at thc notch. The block 16 engages the sides of the cut-out portion of the plate and allows the plate and its associated parts to move slightly but only in the direction in which the pressure is applied, and prevents movement of the plate transverse to the line of pressure. Secured to the block 16 is the stud 1T upon which is mounted roller bearing 18 having a series of rollers 19 surrounded by ring 20.

The condensing roller 2 is of a comparatively1 small diameter. The greatest practical diii'erence in magnitude of the area of contact between the roller and ring and holder and ring is desirable. It is known .from experience in peening or hammering rings, that once established any variation in the relation of these areas, one to the other` such as caused b v the wear of the striking point, etcQresults in a variable product which will not meet the requirements. My condensing rolling method overcomes these difiiculties. B v rolling one half of the ring more than the other and by applyingthe condensing pressure in accordance with a predetermined law.v either b v making use of a tapered roller. or hy utilizing a cylindrical roller shifted toward one side of the central plane of the ring, or otherwise the rolling action will compress and condense half of the ring more than the other and ythrow the forces produced in the metal out of balance, in accordance with the desired law giving uniform pressure and a twist to the ring when the ring is in the cylinder, the twist increasing the pressure at the contacting edge of the ring when it is in the cylinder. The ring in its free state is rolled and the metal condensed in such a Way that when in its confined state within the cylinder it will exert a uniform pressure per unit of contact area. The roll-v er is positioned slightly oil the center line X Y of the pressure applying means, as shown in Figure 8 and is freely movable or floating. It is located olf the center line of pressure X Y and at the near side of the line which a point of the ring approaches before it is condensed. This enables a heavy pressure to be applied to the roller and ring. 0

The condensation in the metal are confined to a radial and circumferential direction, So as to prevent a lateral flow of metal across the width of the ring. Under the law of pressure applied to the ring bythe condensing roller the condensing effect at the points of the ring or 'at zero degrees', is very small. but increases variably to 180. Very near the zero degree the force applied must be suiicient to cause the metal to flow and -permanently condense thru a portion of the annular section'of the ring.- In accordance with the invention this flow is limited to a'circumferential flow and any substantial change in the .width of the face of the blank is prevented which would require correcting opera-tions and introduce further variables. v j

Preferably. the top and bottom rollers` 21 and 21, overlap the flat face of the ring and the condensing roller is shorter than the axial width of the ring. Thus when the ring is-revolved, when it is condensedby the condensing roller 2, the` metal is confined and the condensations are confined to a radial andcircumferential direction. The lines of pressure between the top and bottom roller and the ring should be substantiall)T in the same plane with the line of pressure between the condensing roller and the ring so as to prevent unequal condensations of.

the metal of the top and bottom faces of the rmg.

Pressure is applied to the ring under a predetermined law. The roller 22 is pivoted pn a stud mounted in the slide block 23 which slides in guides 24 in the bed plate. A yielding spring pressure is applied yto the blookx The block carries a stud 25 in the lside opposite the roller which has threaded I 26 and 27.

A heavy `spring 29 is confined between the larger nut 26 and the sliding head 30. A lighter spring 31 is confined between the smaller nut 27 and the head 30. One or all 0f the springs are so set as to exert an initial pressure on the roller 22 which thru the mechanism heretofore described forces the piston ring 1 against the condensing roller 2.

It is desirable when tensioning the ring with one revolution of the holder to start with an initial pressure and under apredetermined law to increase the pressure until the pressure has been applied half way around the ring, at which point maximum pressure is being applied. Then the pres-y sure isdecreased under the same predetermined law until we come backto our startinitial pressure.

ring condensed so as to give, equal ra* dial outward pressure. The result may be checked by a suitable testing gage. 4

The head 30 is mounted to slide in the. aforementioned guides 2l and has pivoted thereto the link 32 which is fulcrulned on the block 33. Pivoted to the opposite end of the link 32 is the connecting rod 34. The other end of the connecting rod carries a slot 35 in which is located the block 36. Thru block 36 p-asses pivot pin 37, thru the lower portion of which passes the adjusting screW 38. 5 l

Means'are thus provided for adjusting the throw of the block'36 which serves as a crank pin.v

The fulcrum block 33` may be shifted at each revolution of the ring when it is derolling steps as explained in my copending application above referred to.

The fulcrum block is provided with a hole 33a into which enters the pin 33b on sliding block 33, the latter sliding in guides 33d. The pinl connection between the two blocks provides the fulcrum. By shifting block 33 the fulcrum is shifted. This may be done by hand by means of a screw 33e threaded to engage the block 33e. On turning the screw by hand at 33t at each lrevolution of the ringthe fulcrum may be shifted -to a new position andthe pressure applied to the ring may thus be increased. The crank pin starting at dea-d center when beginning the rolling operation, the pressure applied to the ring at the points always begins with the same minimum. The fulcrum block can then be brought back to its initial position after the desired number of revolutions of the ring, or this shifting may be done autovmatically.

and is within the cylinder 41. This is shown considerably exaggerated in Eig. 1; the upper portion of which ligure lies toward the explosion end of. the cyhnder.

The radial width of the ring at the compressed portion of a cross-section is less than at the uncompressed portion (see Fig. T) in which the compressed dimension a 1s less than the uncompressed dimension b.

In Fig. 4, a circumferential notch is made in the flat face of the outwardly twisted portion -of-the ring. The notch will thus act to scrape the oil towards the crank case. It also helps to twist the rolled ring. the removal of the metal by means of the notch, unbalancing the stresses so as to cause the ring to twist in the same direction as that produced by the off-center rolling. The ring when rolled so as to give it a uniform twist and uniform radial pressure when confined in circular form within the cylinder will, when in a free state outside of the cylinder assume a non-circular form. It will have a Variable radius of curvature, the shortest at the split the maximum at a point midway of the ring and opposite the split and in between according to the law of rolling. The twist, per unit of length when the ring is in a free state, begins at the points and increases toward the midsection opposite the points. This twist is not great, at the points the twist may be very small, a few minutes of arc and at the midsection the twist maybe 1 or 2 degrees, but of course the amount of twist may vary between wider limits. If' the ring isplaced on a flat plate and its portion opposite the s lit is vpressed against the plate, the points o the ring will rise, the twist having an accumulative effect from the midsection toward the points (see Fig. 5). The angles between the flat faces of the rinof and outer curved face remain substantially right angles but the angles bef and in doing so must control the lubrication and the compression pressure and the working pressure of the charge, the lubrication and the working pressure acting under quite dierent laws. The friction of the ring against the cylinder is reduced.

Having thus described the invention it will be understood that changes may be made therein without departing from the principle of the invention. A

What I claim and desire to secure by Letters Patent is;

l. A rolled twisted ring the metal of the ring being condensed more to one side of the central diametrical zone of the ring.

2. A rolled twisted ring, the condensations of the metal dueto rolling, lying more to one side of the central diametrical zone of the ring, said condensations being so varied, that the ring in its free state will twist in accordance with a predetermined law.

3. A rolled twisted ring, the condensations of the metal due to rolling lying more to one side of the central diametrical zone portion of the ring, said condensations being so varied that the radii of curvature and the angle of twist per unit of length variably increase from points to mid-portion in accordance with a predetermined law, when the ring is in a free state, so that when the ring is conned in a circular cylinder it will translate the stresses into substantially uniform pressure per unit of contact area.

4. A rolled twisted ring, rolled on its inside face, the condensations of the metal due to rolling, lying more to one side of the central diametrical zone of the ring, said condensations being so varied that the ring in its free state will twist in accordance with a predetermined law, and when confined to circular form will exert uniform pressure and a uniform twist around the ring.`

In testimony whereof, I have signed my name to this specification.

ROBERT B. WASSON. 

